#include <cstdio>
#include <cstring>
#include <cmath>
#include <string>
#include <vector>
#define FOR(i, x, y) for(int i = x; i <= y; ++i)
#define rFOR(i, x, y) for(int i = x; i >= y; --i)
#define MS(a, b) memset(a, b, sizeof(a))
using namespace std;
int t, n, m, row, col, len, space, place;
char str[100010];
int main()
{
    scanf("%d", &t);
    getchar();
    FOR(s, 1, t)
    {
        gets(str);
        len = 0;
        while(str[len] != '\0') ++len;
        scanf("%d", &n);
        getchar();
        space = 0;
        while((len + space) % n != 0) ++space;
        m = (len + space) / n;
        row = 1;
        col = 1;
        printf("Case #%d:\n", s);
        FOR(i, 1, m)
        {
            col = 1;
            place = i - 1;
            while(place < len)
            {
                printf("%c", str[place]);
                place += m;
                if(col > n - space) --place;
                ++col;
                if(col > n - space && i == m) break;
            }
        }
        printf("\n");
    }
    return 0;
}